Core bit



Dec. 15, 1953 F. F. DAVIS ET AL 2,662,738

CORE BIT Filed March 25, 1950 q; Fig.3

l r //A 9 8 24A x Q 0T}! s la A X205 37 38 40 /0 I 2 240 4/ 4 a9 4 FRANK FDAV/S l4 STEWART a RICHMOND 20 C Q INVENTORS o a Q Q D BY v M 4 W, 1 5/ A r TORNE rs r I ,2 60A M a a n d a a q 6 J J Z0 4 v v 4 Patented Dec. 15, 1953 CORE BIT Frank F. Davis and Stewart G. Richmond, Minneapolis, Minn, assignors to E. J. Longyear Company, Minneapolis, Minn., a corporation of Delaware Application March 23, 1950, Serial No. 151,484

9 Claims. 1

This invention relates to core bits for rotary drills and more particularly to bits utilizing hard cutting granules, such as diamonds, tungsten carbide or the like as the cutting media.

It is an object of the invention to provide an improved bit capable of much improved performance in respect to bit pressure, bit life and penetration speed.

It is a further object of the invention to provide an improved bit for hard rock core drilling, capable of boring a hole with less deviation than with equipment previously available.

Other and further objects of the invention are those inherent in the apparatus illustrated, described and claimed.

The invention is illustrated with reference to the drawings in which corresponding numerals refer to the same parts and in which Figure 1 is a side elevational view of the apparatus of the invention;

Figure 2 is an end view of the bit end of the device as it would appear from the direction of arrows 2-2 of Figure 1;

Figure 3 is a sectional view taken in the direction and along the line 3--3 of Figure '2;

Figure 4 is an enlarged fragmentary sectional view taken along the line and in the'direction of arrows 4-4 of Figure 2;

Figure 5 is an enlarged fragmentary sectional view corresponding to Figure 4, but showing a modified form of grooving at the bit face.

Referring to the drawings, which are illustrative of the invention, the bit body can be of any form, such as a generally tubular member generally designated id in Figure 3 having a coupling configuration of the bit end and the term bi-t end will be used herein. Member It is of heavy steel tube having a wall thickness T. The tube It is machined down at the thread end ll so. as to provide standard coupling threads HA by means of which the bit may be attached to drill rods for rotation thereby.

At the opposite end the tube I0, is, for exam-v ple, machined to provide a coupling tongue [4 which may be reversed so as to be. a groove, or may be any other keying form or merely a .flat surface to which the bit end is attached by bonding. The tongue (or other attachment groove. or holes) or flat surface M is bonded into a tubular continuation generally designated 20,. which is made of. powdered metal and is sintered or metal cast in place so that it forms a strong bond to and at the end M of tube 10. If desired, portions Ill and 20 may be one piece of metal and the cutting granules hand set therein. The member 20, where separate from member I0, merely forms a continuation of tube I0 and serves as the special anchorage for hard cutting granules of diamond, tungsten carbide or the like, but as explained I9 and 20 may be unitary, if desired.

Referring to Figures 2 and 3, it will be observed that tubular matrix 20 is provided with narrow low longitudinal flutes or lands 2| on the inside and with correspondingnarrow low longitudinal flutes or lands 22 on the outside. These lands protrude from the adjacent surfaces of the matrix 20 by an amount approximately the same height as the protrusion of the hard cutting granules which are located along such lands. The lands project a little beyond the outer and inner surfaces of the tube I 0.

The use of such flutes or lands is an expedient that is useful when the cutting granules are cast or sintered in place in that the bit may be withdrawn from the mold after casting or sintering, without tearing or breaking the mold, since the mold has grooves which form such lands, and these aligned with the cutting granules. When bits are hand set, the lands are not used since the problem of removing the bit from a mold does not exist in the hand-setting operations. Therefore, it is to be understood that the use of lands or flutes is required only when the bit is formed by casting Or sintering. Even in connection with bits that are cast or sintered, the lands or flutes may be eliminated when there is no objection to breaking the mold in which the bit is cast or sintered.

The bit face generally designated 23 has one or more concentric grooves in it, one groove 24 being shown in the bit of Figures 1 and two grooves 511 and 5| being shown in Figure 5. More than two concentric grooves may be used, especially for large bits. In all forms the groove or grooves are in the face of the bit. As shown in Figures 1-4, groove 2 is concentric about the axis of the bit, the groove or grooves, if more than one such concentric-groove is used, can be V-shaped in cross section or simply curved down.- wardly in cross section, or stepped down by a series of steps. In Figures 1-4, which is one illustrative form, the groove 24 has a wall 24B and another similar wall 24C where the two walls 243 and 240 meet to form the bottom 24A of the groove, but. where the walls 248 and, 2.40. are

3 curved in cross section they would be as one and there need not be such an apex 24A at the bottom.

The wall 243 approaches the outer surface A of the end 20, thus forming a slight fiat or cLu'ved ridge 24E which is closely adjacent with the outer surface of tube 15 as shown by the dotted line 28, and the wall 24C likewise meets the inner surface 253 of matrix 28 at the slight flat or curved ridge 24D which is closely adjacent the inner surface of tube It, as shown by dotted line 29. The ridges at the edges of the groove or grooves can be sharp, fiat or curved. Thus, at E and 24D they are nearly fiat with slight curvature, but this is merely illustrative and the shape of the ridge is not critical.

The bit end is set with cutting granules or the entire bit end may be impregnated with cutting granules. For example, in the illustrated bit shown in Figures 1-4 granules are placed or located in, preferably, a somewhat random pattern as at 33-33, Figure 1 on the outer surface 20A, and as at 3-"5-46 on the inner surface 233. As previously explained, the bit illustrated in Figures 1-4 is cast or sintered and, as explained heretofore, ior bits so manufactured the cutting granules may s located along the lands or ridges where it is desired to save the mold.

Also, cutting granules are set, placed or embedded at random along the ridges 2 2E and 2&1), as at 3535 and i-'i6 for ridge ME and at ii-53 and llfor ridge 24D (see Figures 2 and 4), and also along surface 24B-2QA-24C as shown at 52'5i3 (see Figure 2). It will be understood that the particular pattern of setting shown in Figures iis merely illustrative and O noted that in the specifically illusof the invention granules 3t, 35 and ME are set so as to protrude from .y trated for l 35 along e the ridge and slightly away from the axis of the bit, whereas granules (a l, 45 and 8 are along the ridge and protrude in the drilling direction (i. o. parallel to the axis of the bit) while granules such as 53 also along said ridge are tipped so as to protrude slightly toward the bit axis. The same is true for ridge 2 2D.

Across the groove 25 there are preferably provided a plurality of water channels 8t, four being illustrate although more or less can be used for various size bits, and in some instances the water channels can be eliminated entirely. These channels, where used, follow the transverse contour of the groove 25 and are deeper than the groove and hence always provide space for cross flow of drilling fluid. The channels 60 extend from inner surface 233 to the outer surface 29A of bit end 29. Likewise, there may, optionally, be provided slots on the inner surface and slots A on the outer surface which are preferably slanted 9. little and continued up through body it when such slots are used.

In Figure 5, there are two grooves 59 and 5! which are concentric. This form is useful for' larger bite. The pattern of setting the cutting granules is the same as explained above with reference to the bit shown in Figures 2-4. More than two concentric grooves may be used, and as previously explained the grooves may be curve: in cross section.

The depth of the concentric groove in the bit all face is preferably about 10% to as deep as the dimension from surface 20A to 2013, but it will be understood that shallower or deeper concentric groove or grooves are within the purview of the invention. In Figures 3 and 4, which are illustrative, the depth af the groove 24B2 lA-24C is approximately 40% as deep as the distance from 26A to H3. Bits made according to this invention and conforming in size to standard AX bits (U. S. Dept. of Commerce, Diamond Core Drilling Fittings, Commercial Standards 0817-47) and set with 11 to 12 carat weight of diamonds gave i'ootages of 104 feet and 13? feet in a certain rock formation using a drilling pressure of 50 pounds per square inch. The holes were very straight and there was little or no tendency to deviate. By comparison standard type flat face or round nose bits of the same AX size gave footages of about 50 feet and required about 356 pounds per square inch drilling pressure and had a marked tendency to deviate.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments herein.

What we claim is:

1. A bit for core drilling, said bit being in the form of a tube having a coupling portion at one end, the opposite end surface of the tube forming the face of said bit, said face of said tube having at least one groove therein substantially concentric with the axis of the tube and located between the outer and inner surfaces of said tube defining at least two substantially continuous concentric crests at substantially the outer and inner surfaces of the bit, said crests projecting in the drilling direction beyond intervening drilling surfaces or the bit, said bit being characterized by having hard cutting granules embedded in substantially tracking relationship in said concentric crests.

2. A bit of the type set forth in claim 1 further characterized in that the depth of groove is from about 10% to 80% of the distance between the outer and inner surfaces.

3. A bit of the type set forth in claim 1 having a single groove.

4. The bit described in claim 1 further characterized in that the hard cutting granules are diamonds.

5. A bit for core drilling, said bit being in the form of a tube having a coupling portion at one end, the opposite end portion of the tube forming the drilling face of said bit, at least one groove formed in said drilling face of the bit, said groove being substantially concentric with the tube axis, the groove side wall surfaces terminating as substantially continuous concentric ridges substantially at the inner and outer surfaces, respectively, of said tube at the drilling face, said substantially concentric ridges projecting beyond the general level of the drilling face, and hard cutting granules embedded in substantially tracking relation along said concentric ridges, at least some of said hard cutting granules on the inner crest protruding slightly beyond the inner surface and at least some of said granules in the outer crest protruding slightly beyond the outer surface of said tube.

6. The bit described in claim 5 further characterized in that the groove is from 10% to 80% as deep as the thickness of said tube at the drilling surface end thereof.

7. The bit described in claim 5 further characterized in that the hard cutting granules which are embedded along the ridges are oriented so that some protrude from the ridges generally toward and away from the tube axis and some protrude from the ridges generally parallel to the tube axis.

8. A bit for core drilling, said bit being in the form of a tube having a coupling portion at one end, the opposite end portion of the tube forming the drilling face of said bit, a single groove formed in said drilling end of the tube, said groove being substantially concentric with the tube axis, the groove side wall surfaces being a partial conical inner groove surface extending from the deepest portion of said groove towards the inner surface of tube and connected to said inner surface by a smoothly rounded inner ridge and a partial conical outer groove surface extending from the deepest portion of said groove towards the outer surface of said tube and connected to said outer tube surface by a smoothly rounded outer ridge, said inner and outer ridges being substantially continuously concentric with the axis of the tube and substantially at the junction of the drilling face and, respectively, the inner and outer face tube surfaces of the drill, hard cutting granules embedded in substantially tracking relationship along said ridges and in the inner and outer conical surfaces of the groove and in the portions of the tube inner surface and outer surface which are adjacent the ridges, at least some of said hard cutting granules protruding in cutting relation slightly beyond the inner and outer surfaces of said tube.

9. The bit described in claim 1 further characterized in that a plurality of concentric grooves are formed in the face of the bit.

I FRANK F. DAVIS.

STEWART G. RICHMOND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,676,887 Chamberlin July 10, 1928 1,923,488 Howard et al. Aug. 22, 1933 2,136,359 Bley et al Nov. 15, 1938 2,371,488 Williams Mar. 13, 1945 2,371,698 MacFarlane Mar. 20, 1945 2,495,400 Williams Jan. 24, 1950 FOREIGN PATENTS Number Country Date 453,344 Great Britain Sept. 9, 1936 

